Figure 7
(a) A sample of stepanovite from the Chai-Tumus coal deposit (Sakha-Yakutia, Siberia, Russia; collection of E. I. Nefedov). (b) Crystal habit of stepanovite crystals reported by Knipovich et al. (1963). (c) Crystals of the synthetic analog of stepanovite. (d) A single hcb-topology layer in the structures of stepanovite or zhemchuzhnikovite (CSD references: OKUTUL02 and IRUYEB, respectively; Huskić et al., 2016) with Mg(H2O)62+ ions occupying framework pores. (e) A proton-conducting zinc oxalate MOF reported by the Kitagawa group, with adipic acid threaded through channels (CSD reference VUKXUV; Sadakiyo et al., 2009). (f) Stereographic projection of the stacking of layers in the structure of zhemchuzhnikovite, forming channels, with Mg(H2O)62+ guests omitted for clarity. View along the ab plane of the crystal structure of: (g) stepanovite, illustrating the stacking of layers in an ABCA′B′C′ pattern and (h) zhemchuzhnikovite, illustrating the stacking of layers in an AB fashion. |